Crossword clue: to become exhausted; to run out; to fail; -- used generally with out; as, that mine has petered out.
1 answer found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).
Possible answers
disciple of Jesus and leader of the Apostles; regarded by Catholics as the vicar of Christ on earth and first Pope